Morphological comparison of Mesocyclops araucanus Campos et al., 1974, and M. longisetus Thiébaud, 1912, and first description of their males

Originally described by Löffler in 1962 as a variety of Mesocyclops longisetus, M. araucanus was found to have autapomorphies of its own to deserve specific rank. For a long time the identification of these two species were mixed up. Here, M. araucanus female is redescribed and the male described for the first time. A comparison is made with M. longisetus, whose male is also described for the first time. Detailed comparison between these two species shows that the following traits on specimens of both sexes can be used to separate the species: length/width ratio of caudal rami, ratio of terminal caudal setae, and length/width ratio of last segment of endopod of leg 4. Additional diagnostic characters for each sex are given. The geographic distributions of these two species do not overlap.